Preview the demo scene in Unity

Press the Play button. In the Game view you should see a
rendered demo scene.

Note that although the scene here is monoscopic, the rendering on your
phone will be stereo.

Interact with the scene using simulation controls:

Type

Simulated action

What to do

Head movement

Turn your head

Hold Alt + move mouse

Tilt your view

Hold Control + move mouse

Cardboard input

Button press

Click anywhere in the Game view

Build and run the demo scene on your device

Connect your phone to your computer using a USB cable.

Select File > Build and Run.

Unity builds your project and opens the generated Xcode workspace.

Note: If you use Build Settings… > Build to build your project, be
sure to open the generated *.xcworkspaceworkspace file in Xcode, not
the included *.xcodeprojproject file. Opening the project file will
result in build errors.